Why Are There Nets Over East Bidwell Near Flc?

I was driving though E. Bidwell when I saw two sets of nets spanning across overhead the street, hanging by wooden telephone-like poles on each side of the street. Those wooden poles have been there for awhile which makes me think the nets have been put up before regularly. My first thought was maybe they were planning on building something and wanted a safety net of some kind. I don't see any tall trees near by. Anyone know?